1. Field of the Invention
The present invention relates to a dimethyl ether (DME) common-rail fuel supply apparatus and method, and more particularly, to a DME common-rail fuel supply apparatus and method capable of stably maintaining a liquefied state of DME.
2. Description of Related Art
Recently, with the global warming and the rising gasoline prices, all the countries of the world pay attention to DME as alternative fuel which is capable of maintaining the same power level as diesel oil used for partially-changed diesel engines which are being currently mass-produced and reducing particulate materials (PM) and exhaust gas.
Accordingly, a DME common rail as illustrated in FIG. 1 has been applied to develop a dedicated engine. However, there are difficulties in constructing a system, because evaporation (in the case of over −25 degrees or below 6 atmosphere pressures) occurs well due to fuel properties. That is, when the properties of the DME fuel are not maintained, a part such as an injector 4 may be reduced in durability.
FIG. 2 is a graph showing a temperature-pressure curve of the DME fuel. Referring to FIG. 2, it can be seen that the DME fuel maintains a liquefied state around 40 to 45 degrees and 10 bar.
Typically, however, a temperature measured at a point a of FIG. 1 is equal to or less than 90 degrees, and pressure measured at the point a is equal to or less than 3 Mpa. Therefore, referring to the temperature-pressure curve of FIG. 2, it can be seen that the evaporation possibility of the DME fuel is high. Accordingly, there is demand for an apparatus for maintaining a liquefied state of the DME fuel by overcoming such a problem.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.